Electrical apparatus



Dec. 31, 1946'. BENIOFF ELECTRICAL APPARATUS Original Filed June 24,1941 2 SheetsSheet l 194$- H. BENIOFF 2,413,309

ELECTRICAL APPARATUS Original Filed June 24, 1941 2 Sheets-Sheet 2Patented Dec. 31, 1946 ELECTRICAL APPARATUS Hugo Beniofi, La Canada,Calif., assignor, by mesne assignments, to Submarine Signal Company,Boston, Mass, a corporation of Delaware Original application June 24,1941, Serial No. 399,495. Divided and this application February 20,1942, Serial No. 431,685

The present invention is a division of my copending application SerialNo. 399,495, filed June 24, 1941.

The present invention relates to thermionic magnetron tubes of the typein which the tube element forms part of an oscillating circuit and isadaptable for use at extremely high radio frequencies in the range of300 megacycles and higher, especially for high power. The inventionherein described relates to that type of thermionic magnetron tube inwhich the tube elements themselves form parts of a resonant circuit. Inparticular, the anode is in the form of a cavity resonator of a toroidalshape having a concentric slot forming the mouth of the resonator. Thecylindrical cathode is coaxial With the anode and mounted inrelationship with the anode slot as will be more fully understood in thespecification below. The cooperating constant magnetic field is adjustedto such a value as to make the electron orbital frequency substantiallyequal to the resonant frequency of the anode cavity resonator. Thedirection of the magnetic field so created may be either parallel to thetoroidal axis of revolution or parallel to the circular toroidal axis ofrevolution or even perpendicular to the toroidal axis of revolution. Inthese cases the electric field will be arranged perpendicular to themagnetic field and the resultant plane of the electron orbital frequencywill be perpendicular to the magnetic field.

The thermionic magnetron tube of the present type readily lends itselfto constructions using a group of resonators which can be stackedaxially to form multiple resonator systems.

The invention will be more fully described in the specification belowwhich is to be read in connection with the drawings illustrating theinvention in which Fig. 1 shows a vertical section through the center ofthe tube; Fig. 2 shows a vertical section of the modification shown inFig. 1 in which a lurality of resonators are employed, the section beingin relatively the same position as the section of Fig. 1; Fig. 3 shows acentral section through a modified form of the invention shown in Fig.1; Fig. 4 shows a similar central section through another modified form;Fig. 5 shows a section on the line 5-5 of Fig. 1; and Fig. 6 shows astill further modified form in perspective of the invention shown inFig. 1;

In the device illustrated in Fig. 1 the envelope 3B is preferably madeof metal, cylindrical in form, with two fiat ends 31 and 32 through thecenter of which pass the cathode heating leads 33 and 34 which aresealed to the end walls 3| 3 Claims. (Cl. 25027.5)

and 32, respectively, by means of insulating glass seals and 36 mountedon the ends of collars 3'! and 38 extending from th flat ends 3! and 32.Within the envelope 30 the leads 33 and 34 extend outward from thecentral axis into the arms 28 and 29 and support at their verticallyextending ends brackets 39 and 40, respectively, by which the cathode 4|is supported. This cathode, as will be seen in Fig. 5, is a ring towhich current is conducted by the arms 39 and 40 at opposite ends of adiameter so that two halves of the ring are substantially connected inparallel across the leads 28 and 29. The cathode 4| also supports thetop and bottom disc electron shields 21 and 245 by means Of the brackets25 and 24 extending from the cathode 4| and supporting the electronshield discs 25 and 21 in position above and below the ends of thecathode and overhanging the cathode outwardly in the direction of theanode resonator 42. These shields equalize the field potential about thetop and bottom of the hot cathode and prevent electron emission in thedirection of the bottom and top covers 31 and 32, respectively.

The anode 42, as indicated in Fig. 1, is in the form of a split hollowtoroid with an annular slot 43 extending around the toroid concentricwith the cathode 4! and preferably opposite the center. The back wall 44of the toroid may be the wall of the envelope, the whole structure beingsubstantially symmetrical with the central axis of the toroid. Thecavity 45 formed by the wall 44 and the other toroidal walls is spaced,from the end walls 3! and 32 and is placed at a positive potential asagainst the cathode 4| by means of the anode conductor 46 forming thecentral conductor of a concentric cable with the external conductor theconducting tube 47. This conductor 48 passes through an insulating glassseal through an opening 48 in the cavity 45 Where it is connected to thewall 44 at 49, thus coupling with the highfrequency cavity circuitoscillating at a resonance determined by the dimensions and operation ofthe device.

As illustrated in Fig. 1 a magnetizing field is established by the pole59 which provides a cylindrical pole face over the end of the tubeforming a north pole as indicated by the letter N at the to inconjunction with the pole 5! having a similar cylindrical pole facelabelled S providing the south pole at the bottom side face of the tube.The envelope or housing is exhausted of air by suitable means afterwhich it may be sealed off a. the pumping connection 52 in the glassseal 35.

In Fig. 2 a. multiple unit is indicated. In this size to those of Fig.1.

case the metallic housing 53 is made of a longer cylinder as comparedwith that shown in Fig. 1 but it has approximately the same diameter asthat of the device of Fig. 1 with the result that the end cover plates54 and 55 are similar in However, if desired, the device may be made ofa largerdiameter and the spacing of the internal units varied inaccordance with the design desired. In Fig. 2 the cylindrical wall 53supports a plurality of resonating cavities 55, 56, 51, and 58 each ofwhich is provided with annular slots 59, 60, BI and 62, and withindividual cathode elements 63, 64, 65, and 66, all parallelly connectedacross the cathode supply leads Bland 68 which enter through the ends 54and 55 of the unit in the collars 69 and III which are sealed off withglass seals 'II and I2. Each cathode unit may also be supplied with endshields I3 and I4 as illustrated in Fig, 2. It will sufiice in theconstruction of Fig. 2 to take the output lead through a single cavityresonator as illustrated by the conductor I5 which passes through a holeI5 in the wall 53 into one of the resonators 55 where it is connected tothe inside of the wall as indicated at TI. The metallic tube I8 joinedto the cylinder 53 and extending from it forms with the conductor I5 aconcentric cable, which concentric cable is continued as in Fig. 1 bymeans of the conducting tube I9 surrounding the central conductor I5, InFig. 2 the direct current magnetization field is furnished by theelongated coil 8!] in the center of which the magnetic field runsparallel to the axis of the coil.

In the arrangement shown in Fig. 3 a modified form of cavity resonatoris shown. Here the tube assumes a toroidal form with the external walls8|, 82, 83 and 84 forming the toroid and the cavity resonator as twinchambers 35 and 88 with a restricted conducting passage 87 arrangedbetween the two cavities in the center of which is positioned thecathode ring 88 which is supported by the conductors 89 and 90 passingthrough the wall 83 and sealed to the wall by means of the glass sealsSI and 92 in connection with the extending necks 93 and 94 which may beformed as a part of the walls 83. The cathode heating current issupplied through the leads 89 and 9B and the cathode-anode potential issupplied between the leads 89 or 98 and the conductor 9| which links theanode resonator by passing through the wall of the resonator and beingattached to the inner surface of the wall 84 at the point 95. As in theother figures the conductor SI is preferably continued externally of thetube in a concentric cable.

The magnetic field is supplied in the device indicated in Fig. 3 bymeans of the magnet 91 which has a cylindrical north pole positionedopposite one end of the tube and a cylindrical south pole positionedopposite the other end of the tube. In this case the orbits of theelectrons leaving the cathode 88 are maintained substantially inhorizontal planes perpendicular to the magnetic field and the resonanceof the oscillator is determined by the dimensions and construction ofthe cavity and the cathode.

In the modification illustrated in Fig. 4 the cavity ID!) has the samegeometrical form in crosstakes the form of a flat ring in which thecathode surface is positioned in the plane of the ring. The cathode issupported by means of the current supply leads I04 and I05 passingthrough the top wall I86 of the resonator through the tubes I01 and I08and the glass sealing elements I89 and III] as described in connectionwith the previous figures. The anode lead II2 passes through the tubeIII into the interior of the resonator I02 and is connected to one ofthe walls at the inside of the resonator as indicated in the figure.Some latitude is permitted as to the point of connection of theconductor H2. The conductor H2 is brought out of the resonator in aconcentric cable as illustrated in Fig. 1. In this arrangement themagnetic flux travels radially from a central north pole core -I I3 to acylindrical south pole core H4, the core II 3 being placed within thetoroidal element and the cylindrical pole H4 being outside of theelement so that the lines of flux travel radially in the same plane orin parallel planes to the cathode I03.

In the arrangement shown in Fig. 6 a perspective view of a furtherconstruction is illustrated in which the coil 20 surrounds theresonating cavity 22 which has a slot 23 in the inside surface of theresonator wall taking a cylindrical form. The cathode 2i is in the formof a band or ring opposed to the inner wall of the cavity opposite theslot just described. In this construction the magnetic field extends ina direction paralleling the curve of the cathode 2I and the orbitof theelectrons from the cathode 2| is in radial planes perpendicular to thecathode.

Having now described my invention, I claim:

1. A thermionic magnetron tube comprising a casing formed as a toroidalshell, means providing a toroidal resonator shell within said toroidalshell and coaxial therewith forming the anode of a magnetron tube, saidtoroidal resonator shell having a slot coaxial with said resonatorshell, a cathode element also coaxial with said resonator shell andpositioned in opposed relationship with said resonator shell in thevicinity of the slot in said shell and means forming a magnetizing fieldextending in a direction perpendicular to the electric field between thecathode and the anode of the magnetron tube.

2. A thermionic magnetron tube comprising a casing formed as a toroidalelement, a pair of twin toroidal resonator shells positioned within saidtoroidal casing, said toroidal resonator shells having means providingwall elements connecting them together in a common mouth extendingcoaxially with said toroidal resonator shells, a cathode elementpositioned in said common mouth and having its main surface extendingparallel with the walls of the common mouth and means forming a magneticfield extending in a direction perpendicular to the direction of thecathode element.

3. A thermionic magnetron tube having a casing of a toroidal shape, apair of twin toroidal resonator shells within said casing and havingslots therein and cylindrical walls forming a common connecting neckbetween said resonator shells. the said cylindrical walls being coaxialwith the toroidal resonator shells and a cylindrical cathode alsocoaxial with said resonator shells and said cylindrical walls and meanspositioning said cylindrical cathode in the common neck betweensaidresonator shells.

HUGO BENIOFF.

